Patent Literature 1: JP 2009-227276 A
A control apparatus that performs control of matching a specific physical quantity with a target value is widely used in various technological fields. This type of control apparatus performs control of matching a physical quantity (hereinafter, may be referred to as a control physical quantity), which is an object of control, with a target value while feeding back a measured value or measured values obtained by a sole sensor or a plurality of sensors.
A physical quantity measured by a sensor and fed back may be a control physical quantity or may be a physical quantity other than the control physical quantity. For example, the control of matching a vehicle speed of an automobile with a target value may feed back a vehicle speed (control physical quantity) measured by a speed sensor. Alternatively, a physical quantity relevant to the vehicle speed, such as an accelerator pedal depression quantity or the number of revolutions of an engine, may be fed back in place of or together with the vehicle speed.
A sensor, which measures a physical quantity, may fail and output an abnormal value to be fed back, preventing normal control. This may involve, of a controlled apparatus (e.g., automobile), an abnormal operation undesirable in safety.
Thus, a system is provided to include a plurality of sensors each measuring one physical quantity, to attain redundancy and perform normal control continuously even after part of the sensors fails. Such redundancy has been achieved based on various schemes.
Patent Literature 1 discloses a vehicle control apparatus having a plurality of controllers that are interconnected over a network. If a sensor included in part of the controllers fails, measured values of sensors included in the other controllers are obtained over the network and used for control.